Telephony systems connect many different types of equipment having a variety of communication protocols, such as Internet protocol (IP) telephony devices and time division multiplexed (TDM) telephony devices. At the heart of telephony systems, switches provide the mechanism for connecting telephone calls. These switches interface with varied telephony devices using different communication protocols.
Modern telephony systems increasingly use both the traditional TDM protocols and IP communications. Newer telephony equipment often controls both IP and TDM trunks connected to switches linked to telephony networks. However, many legacy applications still interface with switches using equipment designed before the introduction of IP telephony. These applications do not recognize or understand modern protocols such as IP.